Mandela, South Africa's first elected black president, died at his home in Houghton, a suburb of Johannesburg, following a protracted illness. He was 95.
Many celebrities and well known world figures tweeted their shock and sadness at Mandela's demise, the SABC reported.
Twitter itself tweeted a black and white picture of Madiba (Mandela's clan name) with his clenched fist in the air following his release from prison.
People across the globe and specially South Africans expressed their grief.
Former California governor and Hollywood actor Arnold Schwarzenegger tweeted, saying Madiba's life is the closest thing to proof of God.
Golfer Tiger Woods tweeted, "Pop & I felt your aura when we met, I feel it today & I will feel it forever. You have done so much for humanity."
Actress Charlize Theron said she is saddened to the depths of her soul. Olympic sprinter Anaso Jobodwana credited Mandela for his own achievements as an athlete.
There have also been formal tributes from many South Africa sports federations.
A minute's silence has been held at both the cricket test matches under way at the moment, the Ashes in Australia and in Dunedin where the West Indies are playing New Zealand.
Celebrities such as Cristina Milian and Justin Bieber all took to social media to pay their tribute to Madiba.